NEW DELHI — Sri Lanka’s Parliament passed a proposal on Wednesday to remove presidential term limits from the Constitution, paving the way for the popular president to run for a third term and cement his grip on power.

Bolstered by a convincing victory in elections in January and the near-collapse of the main opposition party, President Mahinda Rajapaksa rallied more than the two-thirds majority in Parliament necessary to pass the amendment. The vote came a day after Sri Lanka’s Supreme Court ruled that a referendum was not required to make the change.

The amendment also includes provisions that could prove even more far-reaching by increasing the president’s power to act without oversight, legal experts said.

It removes an independent advisory council that the president currently must consult before appointing people to important nonpartisan posts, like Supreme Court judges and members of the human rights and electoral commissions. In its place will be a parliamentary council without veto power and with only two opposition members.

The amendment puts the president “in control of many independent institutions,” said Rohan Edrisinha, a Sri Lankan constitutional scholar. “That is going to have a serious impact on justice, human rights, free elections and the future of our democracy.”

Mr. Rajapaksa received nearly 60 percent of the vote in January after his government’s decisive May 2009 defeat of the Tamil Tiger insurgency, which had raged for 26 years and defied the efforts of his predecessors to end it. He easily defeated his main opponent, Sarath Fonseka, a former general who had been a close ally. A motley coalition of opposition parties had drafted Mr. Fonseka, who gained popularity for carrying out the ruthless and highly successful military strategy that defeated the insurgency.

After the election Mr. Fonseka was arrested and court-martialed. The government said he had broken the law by politicking while in uniform and mishandling weapons contracts, but his supporters saw the arrest as evidence that the president was solidifying his grip on power by going after opponents.

Sri Lanka’s Constitution features a strong presidency, and many analysts have argued that a country with such a long history of religious, ethnic and regional strife needs to devolve power, not concentrate it. Indeed, Mr. Rajapaksa himself campaigned on promises to give more power to regional governments in Sri Lanka as a way to avoid future conflicts with Tamil and Muslim minorities.

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Mr. Rajapaksa’s spokesman, Lucien Rajakarunanayake, said that given the president’s popularity and the difficult road ahead in rebuilding the country, it made sense to remove term limits.

“This is a president who has a huge mandate and has to do a great deal of work to make sure the country moves forward,” he said.

He dismissed the notion that the abolition of the independent advisory council would make the president more powerful. The previous panel was perpetually deadlocked, he said, and the new body would work more efficiently.

Dayan Jayatilleka, a diplomat and political analyst who was Sri Lanka’s ambassador to the United Nations in Geneva until he was removed in 2009, said that the changes simply formalized the vast enlargement of presidential power that had already take place.

“It is a constitutionalization of the wartime presidency,” he said.

But he added that opposition politicians were as much to blame for this expansion of presidential power. The main opposition party, the United National Party, is in shambles, and several of its members have defected to support Mr. Rajapaksa’s amendment. The Constitution, written when Sri Lanka had a strong two-party system, did not envision that the second party would become so weak, Mr. Jayatilleka said.

“In the past, neither party would be sufficiently popular or unpopular to permit constitutional change,” he said. “Clearly that has changed.”

A version of this article appears in print on September 9, 2010, on Page A13 of the New York edition with the headline: Sri Lanka’s Parliament Ends Term Limits on the President. Order Reprints|Today's Paper|Subscribe